Field of the Invention
The present invention relates to display control of a focus area in a plenoptic image capturing apparatus.
Description of the Related Art
In recent years, a technique called light field photography in which a new optical element is added to an imaging optical system, images are acquired from a plurality of viewpoints, and image processing is performed on the acquired images to adjust the focusing position after image capturing has progressed.
The light field photography has a function called refocusing. The light field photography has an advantage since the focusing can be adjusted by refocusing after image capturing, failure in the adjustment of the focusing during image capturing can be compensated by image processing after image capturing. Further, since it is possible to acquire an image which focuses on various subjects captured by an image capturing apparatus from one captured image after image capturing, the light field photography also has an advantage that the number of times of image capturing can be reduced.
A plenoptic camera in which a microlens array is arranged behind a main lens is known as an example of an image capturing apparatus used for the light field photography. In the plenoptic camera, the microlens array is arranged at a position at which an imaging element (sensor) is arranged in a general image capturing apparatus. Due to such an arrangement of the optical element, light having passed through the right side of the main lens reaches the left side of the imaging element, and light having passed through the left side of the main lens reaches the right side of the imaging element. That is, in the general image capturing apparatus, the light having passed through the main lens is focused on one point. However, in the plenoptic camera, the light having passed through the main lens is separated into the light components entering from the right side and the left side of the microlens. As a result, the plenoptic camera can obtain multi-viewpoint images like the image obtained when the subject is seen from the left side and the image obtained when the subject is seen from the right side.
However, in the light field photography having a refocusing function, like the plenoptic camera, it is still important to align the focusing at the subject during image capturing. This results from the fact that refocusing is performed by integrating the pixel values of a plurality of images imaged at a plurality of viewpoints. This is because, since a subject outside the depth of field of an image capturing lens is imaged blurred, even if the pixel values of the image imaged blurred are integrated, it is difficult to acquire a refocused image after the image capturing.
A focusing checking method in a plenoptic camera is disclosed in Japanese Patent Laid-open No. 2012-142918. According to the method of Japanese Patent Laid-open No. 2012-142918, one image is selected from a plurality of images imaged by a plenoptic image capturing apparatus. The selected image is displayed on a liquid crystal display on the back side of the camera and a user can see a focused image with the naked eyes.